Eleanor, I have the exact same thing with my ancestor, Bushrod Doggett. Family records state that he was wounded at the Battle of Cowpens and carried a crippled arm the rest of his life. No offical record of him serving can be found. William Byars' name disppeared from all records about 1780-81 and many researches think he was killed during the war.
They kept very poor records at the Battle of Cowpens or the records have been lost. Von Hamrick